The present invention relates generally to sacrificial anodes and, more particularly, to a wear indicator within a sacrificial anode for alerting a user when the sacrificial anode has corroded to the extent that it should be replaced.
Any metal in an electrolyte, such as salt water, generates an electrical voltage. When the electrolyte is in contact with another type of metal, electrons (electrical current) flow from a more negatively charged metal electrode or anode to a more positively charged metal electrode or cathode. The circuit is completed by the loss of positively charged ions from the anode into the electrolyte and the deposition of negatively charged ions from the electrolyte onto the cathode. This process results in corrosion or deterioration of the anodic metal material and the protection of the cathodic material.
In order to protect metals, particularly metals which could potentially serve as an anode, within an electrolyte (salt water), a third, more negatively charged metal is often secured to the metal to be protected. The third, more negatively charged metal corrodes “sacrificially” to protect the other two metals. The third more negatively charged metal is commonly referred to as a “sacrificial anode” and is typically made from an “active” metal such as zinc, magnesium, special aluminum alloys or other active metals.
While sacrificial anodes are very effective in protecting other metals, particularly the protected metal to which the sacrificial anode is secured, eventually a sacrificial anode wears out due to corrosion and its effectiveness in protecting the attached metal diminishes. Typically, in order to maintain effectiveness, the sacrificial anode must be replaced when the sacrificial anode has corroded to approximately one half of its original size. In order to know when a sacrificial anode has reached one half of its original size, it is usually necessary for a user to know the original size, a task which is often difficult. As a result, users typically replace sacrificial anodes before the useful life of the sacrificial anode has been exhausted, thereby wasting at least a portion of the useful life of the sacrificial anode. Alternatively, users wait too long to replace the sacrificial anode thereby potentially causing corrosion or deterioration of the protected metal. The present invention comprises an apparatus for eliminating such uncertainty by providing a user with a positive easily discernable indicator of when it is time to replace a sacrificial anode without undue risk to the protected metal and without undue waste of the sacrificial anode.